Hot Times for Solar Energy

Fly into the surreal rainbow glow of the Las Vegas strip
at twilight and it becomes clear why the state of Nevada
has become a metaphor for the energy crossroads confronting
the United States. The city’s hunger for electricity,
like its visitors’ appetite for carnal indulgence,
is insatiable; it is the seat of Clark County, the second fastest
growing county in the United States. Nevada’s two public
utilities project that the state will hit an electricity capacity
shortfall of 2,100 megawatts by 2016 if more isn’t built.

The vision of a future powered by fossil fuels in one of the
sunniest spots in the world strikes many people, including
Harry Reid—majority leader of the U.S. Senate and a strong
opponent of coal-fired plants—as ludicrous. Which is why
Nevada has emerged not only as the biggest battleground
over coal but the newest test bed for utility-scale solar thermal
electricity. Its advocates believe it can and should become
a large piece, along with other renewable-energy sources, of
our energy future.

Solar thermal technology, also called concentrating (or
concentrated) solar power (CSP), uses huge arrays of mirrors
to focus sunlight and make steam to run a conventional
turbine generator. The photovoltaic solar power systems used
mostly on rooftops, in contrast, allow the energy of solar photons
to create an electron flow using semiconductors. CSP
provides “peak” power to feed the midday hunger for air conditioning
and other loads, but with the addition of thermal
storage CSP energy can also be banked for later use long past
sundown. This could overcome one of the major obstacles to
deploying solar power on a large scale.

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